This invention relates generally to shuttleless looms with reciprocating weft inserting grippers and in particular to an actuating mechanism for such weft inserting grippers.
As is known, in shuttleless looms, the weft thread is inserted by means of two suitably designed grippers (sometimes called needles or darts, depending on their different shapes). During the long standstill phase of the comb and related opening of the shed, the two grippers, which are carried cantilever-fashion by the respective sides of the loom, are first moved toward each other, starting from such sides, and then, after meeting at the center of the loom and handing over the weft thread, returned to the loom sides to allow the comb beating up.
Also known are shuttleless looms wherein each such gripper is secured at one end to a respective flexible belt, arranged to slide in a sort of arcuate guide. The two arcuate guides extend in a horizontal plane lying parallel to the loom front and project out of said sides, and sometimes depend downwards from the loom, such as not to interfere with the oscillations of the sley to which the comb is mounted. Moreover, each belt is provided with a lengthwise series of slots, in mesh engagement with the teeth of a respective gear or toothed wheel which is driven to reciprocate rotatively in either direction, thereby the belt is moved out of the guide and the related gripper is brought to the loom center, and viceversa, the belt is withdrawn and the gripper moved back.
Numerous are the aspects of the types of control utilized in the past for such gear wheels which have failed to prove fully satisfactory. For example, with the currently employed controls, the belts of the weft inserting grippers do not have sufficiently low speeds and accelerations to ensure, at the gripper travel limit corresponding to the loom center, a correct transfer of the weft thread from one gripper to the other. Furthermore the bulk size of the looms is considerable, and so are the travel sections covered by the grippers during their return stroke after leaving the reed.
Other drawbacks are due to the conventional controls being less than entirely suitable for application to looms having, within a certain range, a front of different useful extension.
This invention sets out to obviate the cited shortcomings.